can somebody explain how I can either pass base X11 -geometry into a
java application, or set state into .Xdefaults and/or wm to allow them
to identify Java apps, and make them DTRT?

I run tvtwm. it is a known bogon of virtual desktop so it is probably
my WM, but I just cannot make java apps start up outside of the real
'top left' 0,0 window. They do randomplacement in that window, but I
have to drag them into other panes, and any subsidiary popup winds back
in that quadrant.

I can't find a pointer to where java honours the base X11 flagset. I
thought all well-behaved X apps had to honour things like -geometry and
the backing-store directives?

-George